Automatic brake control



Dec. 28, 194s. A. o. ROBERTS ET AL 2,457,729

AUTOMATIC BRAKE CONTROL Filed April 19, 1945 Patented Dec. 28, 1948 ,i

UNITED STATES .PATENT ori-ICE AUTOMATIC BRAKE CONTROL Albert 0. Roberts and John J. Wharam, Dearborn, Mich., assignors to Ford Motor Company, Dearborn, Mich., a corporation of Delaware Application Apru 1s, `194s, serial No. saam 'z claims. Awi. 19a-3) This invention relates tohydraulic torque consystem installed on the car to operate the veversion devices of the type employed on motor vehiclc brakes, and is quiet and certain in operation hicles; and, more particularly. to an automatic and effective 9,1-, all times, anticreep device to be incorporated in such de- `With these and other objects in view, the invices to overcome the creeping effect of Fottinger vention consists in the arrangement described ini type rotors operated atidling speeds. the speciilcation, claimed in the claims, illus- The general type of transmission which is contrated in the accompanying drawings, in which:

u templated is shown in ourcopendlng application Figure l is a longitudinal cross sectional view 574,652, led on January 26, 1945, vnow matured of a hydraulic transmission embodying the presnto United States Letters Patent' 2,404,657, isl0 ent invention.

sued July 23, 1946, and reference may be made Figure 2 is an enlarged longitudinal section to it for a more complete discussion of the 4adthrough the pressure retaining device applied ln vantages of the particular type shown. However, carrying out the invention, the mechanism conthis transmission-as do all of -those employing necting therewith being shown diagrammatical- Fottinger type rotors as the hydraulic coupling l5 ly.

or torque conversion unit-is characterized by Figure 3 is a mod-ined clutch plate design which tendency to creep at idling speeds which requires may be used in place of lthe conventional clutch constant braking on the part of the operator' to facing shown in Figure 1.

hold the vehicle at rest. A number of expedients As noticed' above, the transmission ls of the have been proposed lto overcome this defect, general type shown in our United States Letters which is inherent in the coupling; but, as a last Patent 2,404,657, and fora complete description resort, it is almost universal practice to advise of its construction, reference is made to that inthe operator to rely upon his emergency brake or strument. It suilices to note here that it comtc hold the service brake engaged during idling prises basically, a torque converter III employing periods. This is practicable from a mechanical a Fottinger type coupling vIII and a ygearbox I2 standpoint, and is entirely eilective so long as the enclosing a planetary gearing system i3. The operator remembers to apply the brake. Yet, not coupling or conversion unit II includes the iminfrequently, this precaution is overlooked and peller rotor il fixed for rotation with the iiywheel the car will begin to move when the engine is op- IB which, in turn, is secured in the usual manner erating at idling speed and when, normally, the to an engine crankshaft. The reaction rotor It established torque paths through the transmlsis mounted through the intermediary of an oversion are disengaged. The advantage of thejpresrunning clutch Il on the sleeve I8 which is rigident construction is that a brake is provided which ly secured to the converter hoi sing I9 flxedly seoperates automatically and which obviates the cured to the engine. The runner 2i is mounted disadvantages inherent in systems which require 36 on the hub 22 which is splined at 23 to the transthe direct attention of the operator. Anothjr admission shaft 24, journaled at 25 in the flywheel vantage with the present system is that it uti- II. A clutch plate 26 is secured to the hub 22 and lizes, as an activating element, portions of the has a peripheral clutch facing 21 adapted to cobraking system already applied on the motor veoperate with-the face 28 on the ilywheel I5.

hicle, reducing the Vcost of the installation. Still The engagement, of the clutch is effected another advantage is that the control of the antithrough the pressure of the hydraulic iluid within creep device is interlocked with the operating the converter housing as controlled by the cencontrols of the vehicle so that when these latter trifugally operated valves 29 and 30 mounted on controls are operated in the normal manner to the flywheel I5 and clutch plate 2-6, respectively. bring a vehicle to a stop, the antlcreep brake is' 45 The valve 29 comprises a casing 32 in which the automatically activated and. when the controls dumbbell valve 33 is arranged to slide radially are operated to increase the engine speed above withrespect to the axis of the transmission and idling, .the brake is automatically disengaged. is normally resiliently urged Ainwardly by the This provides positive assurance that the antispring 34. An oil duct 35extends through the creep brake will be applied under those conditions casing 32 and the body of the flywheel I5 adiain which it is required, and that this application cent the annular oil groove 38 in the clutch facing will be eected merely through .the normal opera- 21. It is apparent that the valve 29 is normally tion of the vehicle. A further advantage of the closed, but that when the rotation of speed of present construction is that it is'operated hythe flywheel increases, beyond a certain point. draulically making use of the general hydraulic it will open and permit free ilow from between the clutch facing and the rear face of the ilywheel to the space forwardly of the flywheel.

, The valve 30 includes a casing 31 in which a plunger valve 38 is radially arranged with respect to the shaft of the transmission and is normally urged inwardly by the spring 39. An oil duct 4I extends through the casing 31, the clutch plate 26 and the clutch facing 21 to the radial oil groove 42 intersecting the annular groove 86. This Valve is normally open when the clutch plate is not rotating or is rotating at low speeds. However, the centrifugal force imposed will cause it to close as the clutch plate speed exceeds a. predetermined minimum, The precise operation of the clutch is described at length in United States Letters Patent 2,404,657 and will not -be repeated here.

The gearing system referred to above comprises the shiftable drum 43 slldably mounted on the forward extension 44 of thedriven shaft 50, which is rotatably mounted on the rear end of the transmission shaft 24. The extension 44 terminates an internally toothed drum 45 engaging a planet pinion 46, rotatably supported on the carrier 41, which, in turn, is rotatably mounted on the rearward extension 48 of the brake drum 48. The brake drum 49 is encompassed by a conventional hydraulically operated contact-ing brake band I, permitting engagement of the gearing Without the interposition of a separate clutch, which is anchored to the gearbox housing. The drum 43 carries an internally disposed selector ratchet 52 engaging with the ball selector 5.3 on the carrier 41, permitting common rotation of drum 43 and carrier 41 in different relative longitudinal positions. The brake drum 49 is splined to the shaft 24 at 58 and the pinion 46 also engages the sun pinion 59 integral with lthe shaft.

As shown in the drawing, the transmission is in neutral position. Moving the drum 43 one step towards the left engages the forward speed through the driving engagement of the carrier 41 with the drum 43, and the engagement of the internal ring gear 54 on the brake drum 49 with the external gear 55 on the shiftable drum 43. Reverse operation is obtained by moving the shiftable drum 43 one space to the right of neutral position leaving the carrier 41 and the drum 43 fixed for common rotation, and the reaction is provided by the internal ring gear 56 secured to the housing engaging the external gear v55 on the drum 43. A complete lock is obtained by moving the drum 43 one step further to the right in which case the second external gear 51 on the drum 43 engages the internal gear 54 on the brake drum 49, and the external gear 55 is locked to the housing through the ring gear 56.

The invention, in the present application, is deemed to reside in the means which are used to rprevent creep at idling speeds. Of course, in the broader aspects, this is equally applicable to any vehicle application in which automatic setting of the brakes is desirable and in which release may be eiected by operation of the accelerator. In the present instance, Figure 2 shows diagrammatically, one such hookup applied to a vehicle having the usual hydraulic wheel brakes and a transmission brake of the type shown in Figure 1. In this View, the brake pedal is indicated at 60 and its depression operates the master cylinder 6|. The operating fluid under pressure from the cylinder operates the regular wheel brakes through the duct 62 and is also transmitted to the pressure maintenance device 63 through the duct 64. It is usual in hydraulic brakes to maintain the fluid in the brake lines under a minimum pressure less than that required tooperate the brakes which has been found helpful in preventing leakage. 'I'hls basic pressure maintenance device is here incorporated in the master cylinder and is effective throughout the system beyond the cylinder. In addition, the pressure maintenance device 63 is set to maintain a somewhat higher pressure in that portion of the system beyond it, sufficient to operate the brakes in the portion of the system controlled by it. but provided with means to relieve this higher pressure to disengage the brakes. Here the pressure relief is eected by the accelerator 65 which, on depression, operates the throttle valve in the enbine carburetor in the usual manner and-rotates the control shaft 8| of the pressure maintenance device through the Y link 66. The duct 82 leads to the transmission brake operating cylinder connected with the brake band 5| of Figure l.

The pressure maintenance device 63 includes a principal chamber 61 in direct communication with the duct 64 from the brake master cylinder and is, of course, subjected at all times to brake fluid under the pressure imposed by the master cylinder. It also4 includes a retaining chamber 68 separate from the principal chamber 61 by the valve mechanism 6 9. includes an annular rubber washer 10 formed about a metallic reinforcing washer 'H and normally urged into sealing engagement with the wall 12 separating the two chambers by means of a spring 13. The central aperture in the annular washer 10 is normally closed by a plunger valve 14, resiliently urged into sealing engagement by the spring 15. The valve 14 has an extending shank 16 engaging the shaft 11 which is mounted for reciprocal movement in the cross wall 18 and has its outer end engaging a cam depression 19 in the head 80 of the operating shaft 8i. The cross Wall 18 is threaded in the casing and may be advanced or retracted to adjust the eiect of the spring 13.

When the master brake cylinder 6i is operated, the fluid in the principal chamber 61 is subjected to considerable pressure and the plunger valve 14 is opened equalizing the fluid pressure in the retaining chamber 68. Thus the wheel brakes are operated through the duct 62 and the transmission brake through the duct 82 in the particular hookup shown. When the brake pedal is released, the pressure in the lines to the wheel brakes begins to drop to the minimum established by the master cylinder pressure control and the same condition applies in the principal chamber 68 of the pressure retaining device 63. However, this reduction in pressure permits the seating of the plunger valve 14. The pressure in the retaining chamber 68 is then somewhat higher and the annular valve 18 will be unseated until the pressure in the retaining chamber reaches a predetermined minimum level determined by the resistance of the spring 13, when the valve 1U will again close. This structure is basically the same as that usually employed in the master cylinder, but the spring 13 is so proportioned that a substantially higher pressure is maintained in the retaining chamber and hence in the line 82 leading to the transmission brake than obtains in the lines 62 leading to the wheel brakes. The brakes themselves are so constructed that they will not engage at the lower pressure, but will be engaged at the minimum pressure obtaining in the retaining chamber and in the transmission brake line. Thus, when the brake pedal is depressed This valve mechanism brake pedal is released, the wheel brakes are disengaged (although the uid in the line 62 remains under a predetermined minimum pressure) while the transmission brake because of the higher pressure maintained by the pressure retaining device 63 remains engaged and the brake drum do is restrained against rotation even after the brake pedal is released. It is thus apparent that after the brake pedal is applied. the transmission brake remains engaged after the pedal is released.

Complete release of the transmission brake is effected by having the accelerator 66 of the vehicle so interlocked with the operating shaft Iii oi the pressure retainingA device 63 that whenthe accelerator is depressed the head 80 is revolved and the shaft Tl is forced toward the left as it leaves the eccentric depression 19. 'I'his, in turn, pushes the shank 16 of the plunger valve 'M towards the left against the urging of the spring l and permitsthe pressure or the fluid in the retaining chamber 68 to be equalized with that obtained throughout the brake line. The resultant hydraulic pressure is the standard minimum at which all the brakes are designed to be disengaged and, accordingly. thea transmission brake is released and operation oi the gearing system is permitted.

From the foregoing, it will be noted that the mere routine activation oi the vehicle, brake pedal sets the transmission brake which remains in engagement, even after the brake pedal is re-l leased, until' such time as the vehicle accelerator is operated. This provides a direct anticreep protection through the transmission brake: and this braking operation is entirely automatic--both as to engagement and release-and follows directly upon the normal operation of the'vehicle, since it is always necessary to depress the accelerator4 to some extent vbefore forward movement can be resumed, A

Figure 3 shows an alternative construction for the clutch plate in which, in place oi the customary clutch facing, annularly toothed or ridged interlocking metal clutch elements are used", those on the flywheel vIl beingindicated as ou and those on the clutch plate 92 as B3. [In order to permit the escape'of oil from the roots of the teeth ,98, radial bleeds 94; are drilled inwardly at suitable intervals from the rim oi the flywheel and plugged as at 95.`Bimilar bleeds 98 are drilled to permit the escape of iluid from the root oi the clutch plate teeth 93 leading to the outer periphery-oi' the clutch plate. A ductll leads throughfthe web of the flywheel and connects to a valve of the type shown at Erin Figure 1. struction is particularly eil'ective underlarger loads and is easily engaged and disengaged innder the slighter pressure diil'erentials. i

The advantages oi' .the construction sh will, it is believedt-be instantly apparent to tliosaA sinned in this art. The need has been recognized for some type of automatic breaking control when the engine is idling. The diillculty has been to obtain such a control in the course of normal operation of the vehicle. without reliance' upon the specic attention of the operator to eilect it. In the present case.,this is accomplished since any routine operation of the main brakes sets the auxiliary brake. Yet the auxiliary brake is immediately released when, following the routine operation of 'the accelerator before forward movement is resumed, the pressure existing in the auxiliary brake lline is reduced to a point at which this brake is released. Thus, the colistruction is entirely automatic and extremely l simple to operate and build.

Some changes may be made in the arrangement, construction, andkcombination of the various parts of the improved construction without departing from the spirit of the invention, and it is the intention to cover by the claims such constructions as 'may reasonably be included within the scopeV thereof.

We claim as Vour invention:

1. In an automotive control device, for vehicles having a transmission brake and a plurality of wheel brakes, a brake operating pedal, brake activating means effective on operation of said pedal to operate both said wheel brakes and said transmission brake, means associated with said brake activating means effective on release of said brake pedal to disengage said wheel brakes while retaining engagement of said transmission brake, an accelerator control, and an interlock between said accelerator control and said associated moans to disengage said transmission brake on operation oi said accelerator` control.

2. In an automotive control device for vehicles including a fluid transmission having associated therewith a transmission brake and a plurality of wheel brakes, a brake operating pedal, brake activating means effective on operation of said pedal to operate both said wheel brakes and said transmission brake, means associated with said brake activating means eilective on release of said brake pedal to dlsengage said wheel brakes while retaining engagement of said transmission bra-ke, an accelerator control, and an interlock between said accelerator control and said asso- 'ciated means to disengage said transmission This oonbrake on operation of said accelerator control.

3. In an automotive braking system, a vbrake pedal, an accelerator control, a first braking means, a second braking means, a hydraulic brake master cylinder effective on operation of said brake pedal to supply iluid to the lines leading to said braking means under pressure sumcient to operate both said braking means and on release of said pedal to diminish said pressure at the master cylinder below a point suiiicient to maintain engagement of both said braking means, pressure retaining means interposed in the line leading to said iirst braking means ei'- iective on said release to maintain suillcient pressure at said rst braking means to continue engagement of said first said braking means, and a connection between said accelerator control and said pressure retaining means, effective on operation of said accelerator control to diminish said last-named pressure at said first breaking means to disengage said first braking means.

4 In an automotive control device, a hydraulic transmission, a hydraulic brake incorporated in said transmission, a brake pedal, an accelerator control, a plurality of wheel brakes, a hydraulic brake master Vcylinder effective on operation of said brake pedal to supply iluid to the lines `leading vto said braking means under pressure suiflcient to operate both said wheel and transmission brakes and `on release'of said brake pedal to diminish said pressure at said master cylinder below a point suillcient to maintain engagement oi' both said wheel and transmission brakes, pressure retaining means interposed in the line lead,-

transmission brake to continue engagement of said transmission brake, and a connection between said accelerator control and said retaining means, effective on operation of said accelerator control to diminish said last-named pressure at said transmission brake to disengage said transmission brake.

5. In a hydraulic braking system, a brake pedal operating a master cylinder, a plurality of fluid supply lines leading from said cylinder to individual brakes, means at said cylinder to maintain a predetermined minimum pressure in said lines insufficient to operate said brakes, a pressure retaining means in the line to at least one said brake effective to maintain pressure up to a predetermined minimum the pressure established by the operation of the pedal after operation and release of the pedal, said predetermined minimum being sufficient to maintain said one brake in engagement, and selectively controlled means to render said pressure retaining means inoperative and to disengage said one brake.

6. In an automotive control device, a brake pressure retaining means including a casing, a brake pedal operating a master cylinder supplying fluid under pressure to a first chamber in said casing, a second chamber in said casing, a valve between said chambers adaptedv to permit flow of iiuid from said first to said second chambers on operation of said brake pedal and to close on release of said brake pedal, a second spring loaded valve in said pressure retaining means between said chambers effective to release fluid from said second chamber when said brake pedal is released until a predetermined minimum pressure is obtained in said second chamber,

and selectively controlled unseating means effec# 7. I n an automotive control device, a brake pressure retaining means including a casing, a brake pedal operating a master cylinder supplying fluid under pressure to a first chamber in said casing, a second chamber in said casing, a valve between said chambers adapted to permit flow of fluid from said first to said second chambers on operation of said brake pedal and to close on release of said brake pedal, a second spring loaded valve in said pressure retaining means between said chambers effective to release fluid from said second chamber when said brake pedal is released until a predetermined minimum pressure is obtained in said second chamber, and selectively controlled unseating means effective to unseat said iirst valve to permit equalization of pressures in said two chambers, said unseating means includes a shaft rotatably mounted in said casing, an eccentric cam formed at inner end of said shalt, means effective between said cam and said first valve to unseat Vsaid valve, and a connection between said shaft land the accelerator of a vehicle upon which said control device is installed adapted on operation of said accelerator to rotate said shaft to equalize the fluid pressure in said two chambers.

ALBERT O. ROBERTS. JOHN J. WHARAM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,724,568 Durning et al. Aug. 13, 1929 1,799,495 Bendix Apr. 7, 1931 2,028,491 Barrett et al Jan. 21, 1936 2,030,288 Freeman Feb. 11, 1936 2,080,295 Wheeler et al May 11, 1937 2,151,278 Milhaupt Mar. 21, 1939 2,262,842 Goepfrich Nov. 18, 1941 2,285,781 Patrick June 9, 1942 

